ViewNX shows wrong thumbnails

This question is addressed to any and all Nikon ViewNX software users out there.

I seem to have an odd problem; if I display thumbnails at smaller than the two largest sizes, e.g. where 3 or more fit across the screen, I see the wrong thumbnail image for a given filename. If I make the thumbnails either of the two largest sizes, e.g. so only two fit across the screen, the correct image is shown.

It is only the thumbnail picture that is wrong, the filename text and rating, etc. all belong to the correct image in that folder. The number of files affected seems to be on the increase. I haven't figured out a pattern to it yet. The 'wrong' pictures shown may not even be in the same folder. Changing sort order has no effect, nor grid or list view, niether does closing and opening ViewNX. I have tonight updated to the latest version of ViewNX (1.4), but all this did was change the 'wrong' image being shown.

I haven't found a means to rebuild thumbnails, re-index or refresh the view, that fixes this.

As to what might be causing it; I am editing images in PSE6 (opened from within ViewNX), and I am saving back into the same folder, the new pics appear at the end of list or grid OK. However, it must be associated to this activity as it doesn't happen in folders where I haven't yet edited and saved back any images. The whole lot is on an external USB connected HDD, although I doubt that's relevant.